Gas stream heater

ABSTRACT

Burner for heating a gas stream wherein a portion of the gas is diverted from the main conduit to a burner tube into which fuel and air are injected and burned and from which the heated diverted gas and combustion products are reintroduced into the main conduit approximately concurrently with the stream therein. For this purpose the burner tube is disposed generally at an acute angle with respect to the axis of the main conduit and the burner tube outlet extends into said conduit. In the burner tube a baffle is provided to impart a swirling motion to the diverted gas as it enters the burner tube. The injection nozzle is surrounded by a perforated cone which is in turn surrounded by a cylindrical member with a smaller annular passageway therearound.

[/1968 Reed Primary Examiner-John J. Camby Attorney--Paul & Paul ABSTRACT: Burner for heating a gas stream wherein a per main conduit to a burner tube into which fuel and air are injected and burned and from tion of the gas is diverted from the products are ately concurpurpose the burner which the heated diverted gas and combustion provided to impart a swirling motion to the diverted gas as it enters the burner tube. The injection noule is surrounded by a perforated cone which is in turn surrounded b y a cylindrical rearound.

263/19 A member with a smaller annular passageway the United States Patent 172] Inventors Harold R. Smithson West Town; John M. Hansen, Malvern, both of; Pa. 21 AppLNo. 865,074 22 Filed' 0cl.9,l969 [45} Patented July 20, 1971 I73] Assignee Oxy-Catalyst, Inc. West Chester, Pa.

[54] GAS STREAM HEATER 6 Claims, 3 Drawing Figs. 52 us. c|........

5| 1m. x [50] FieldofSearch............. .......1...............t.....

[56] References Cited UNITED STATES PATENTS 1,650,342 11/1927 PATENTED JuLeolsn 3, 599,959

sum 1 ur 2 INVENTQRS. Harold R. Smithson BY John M. Hansen ATTORNEYS.

PATENTEUJUL20|91| SHEET 2 (IF 2 INVENTORS Horolcl R. Smithson By John M. Hansen Mv M ATTORNEYS.

GAS STREAM HEATER The present invention pertains to a burner for heating a stream of gas. More specifically, it pertains to a heater device for effectively and efficiently diverting a portion of the flowing gas stream through a combustion space and then mixing the heated, diverted gas and combustion gas products back into the main stream of the flowing gas with a minimum of pressure drop.

There are various applications for burners to heat flowing gas streams and/or to cause combustion of unburned products therein. Three particularly desirable attributes of such burners are: (1) minimum pressure drop from inlet to outlet, (2) efflcient use of fuel and effective heating of a gas stream thereby, and (3) minimization of contamination of the gas stream and of the burner by unburned or partially burned fuel products.

It is an object of the present invention to provide a burner heater which possesses these attributes to a high degree.

Briefly, the present invention comprises a burner in which approximately l5-25 percent of the gas stream to be heated is diverted from the main conduit into a separate burner tube where it is heated and then returned to the stream in the main conduit. To ensure good mixing of the heated and unheated gas and minimum pressure drop, the burner tube is disposed at an angle of up to 90; preferably on the order of l5"-25, with respect to the axis of the main conduit and extends into and is in communication with the main conduit and has its outlet near the axis thereof. Heated gas and burner tube products thus enter the central portion of the main conduit flowing approximately cocurrently with the unheated portion of the gas stream therein. The gas diverted from the main gas stream into the burner tube is divided into a smaller portion which flows through an annular passageway provided by a cylindrical casing within the burner tube effectively sweeping the walls of the tube preventing deposition of combustion products or unburned fuel thereon. The second and larger portion of the diverted gas, is given a swirling motion by a baffle disposed near the inlet to the burner tube and then flows through a perforated cone within the cylindrical casing and surrounding an injection nozzle. Fuel and air, injected from the nozzle, are mixed and swirled with the gas to be heated, and ignited by an ignition means, such as a spark plug, located downstream thereof. The heated, swirling mixture of diverted gas and com bustion products is then delivered back into the main conduit of the flowing gas stream.

The present invention may be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which FIG. 1 is a sectional view of the burner of the present invention;

FIG. 2 is a sectional view of the burner shown in FIG. 1 along the line Il-ll in FIG. 1; and

FIG. 3 is a partial sectional view of the burner shown in FIG. 1 along the line IIIIII in FIG. 1.

Referring more specifically to FIGS. 1, 2, and 3, there is shown a conduit for a stream of gas flowing generally from right to left, a burner tube 12 of approximately the same diameter as conduit 10, disposed at an angle of up to 90 with respect to conduit 10. Preferably, this angle, as shown, is on the order of l5-25. Burner tube 12 extends into conduit 10 and the outlet 12A thereof is disposed near the longitudinal axis of conduit 10. A back pressure means [4, in this case a perforated annulus, is interposed in conduit 10 to produce a slight back pressure region upstream thereof, in which region is located a diversion means 16 for diverting a portion of the gas flowing in conduit 10 into burner tube 12. As illustrated, diversion means 16 may comprise a partially cutaway tube. More specifically, there is shown a semicylindrical member extending across the path of gas flowing in conduit 10 and having a tubular portion 16A which forms a passageway for the diverted gas into burner tube 12.ln order that a significant but not excessive amount of gas be diverted from the stream in conduit 10 into burner tube 12, it has been found that the projected cross-sectional area of the diverting means 16, more specifically the area of the diverting means projected in a plane perpendicular to the axis of conduit 10, should preferably be on the order of l5--25 percent of the cross-sectional area ofconduit 10.

At its inlet end 128, burner tube 12 is provided with a bafflc 18 which imparts a tangential movement to the gas entering burner tube 12 from diverting means 16 causing the diverted gas to swirl about the axis of burner tube 12 as it moves thcrethrough. A perforated cone 20 near the apex of which is disposed an injection nozzle 22, to which is supplied fuel and air through fuel supply means 24 and air supply means 26, is surrounded by a cylindrical member 28, the diameter of which is preferably on the order of *-95 percent of the diameter of the burner tube. An annular passageway 30 is thus formed between cylindrical member 28 and the outer wall of burner tube 12 so as to form a bypass for a portion of the diverted gas entering burner tube 12 through inlet 12B. This bypassed gas provides a sweeping action along the walls of burner tube 12 downstream of cylindrical member 28, perforated conical member 20, and nozzle 22. An igniter means 32 is also provided downstream of the cylindrical member 28, conical member 20, and noule 22, to ensure continuous combustion of fuel and any other burnable constituents in the diverted gas stream.

lgniter means 32 is illustrated as a spark plug, although a variety of other types of igniters may be substituted therefor. Injcctionnozzle 22, as shown, is intended for use with diesel fuel. For this purpose an injection nozzle manufactured by the Sonic Development Corporation, Yonkers, N.Y., has been found to be suitable. Other types of nozzles may also be used, particularly in embodiments of the invention where other fuels, such as natural gas, are used.

In operation, the burner of the present invention has been found to be highly effective to heat a stream of flowing gas by diverting and heating a portion thereof and reintroducing the diverted gas into the main stream with a minimum of pressure drop. Further, the swirling and sweeping action of the diverted gas in the burner tube of the present invention ensures maximization of combustion of the combustible products therein and minimization of deposition of unburned or partially burned fuel products in the burner and contamination of the gas stream with such unburned or partially burned products. Moreover, the effectiveness and efficiency of this burner has been found to be maintained despite surging, back pressure, discontinuities, and unevenness in the flow of the gas stream. Such a burner has been found, therefore, to be particularly effective as a means for heating the exhaust gases from large diesel engines, such as are used in large trucks, tractors, earthmoving equipment, mining equipment, standby gcnerating equipment, and construction equipment generally prior to the introduction of these exhaust gases into catalytic emission control devices.

Having described our invention, what we desire to claim and secure by Letters Patent of the United States is:

l. A burner for heating a stream of gas comprising a. a main conduit through which said gas flows in a predetermined longitudinal direction,

b. a burner tube, forming an angle of up to 90 with the longitudinal axis of said conduit and extending into said con duit with said burner tube outlet disposed near the longitudinal axial center of said conduit such that gases flowing from said burner tube enter said conduit flowing generally cocurrently with the gas in said conduit,

c. back pressure means in said conduit disposed upstream of said burner tube outlet to produce a slight back pressure just upstream of said back pressure means,

d. diversion means, disposed in the back pressure region formed by said back pressure means, for diverting a portion of the gas in said conduit, into said burner tube inlet,

e, an injection nozzle, disposed in said burner tube, with means for supplying feel and air thereto, an igniter means disposed in said burner tube between said nozzle and said outlet,

g. a perforated conical member disposed in said burner tube with said nozzle at its apex, and its base between said nozzle and said igniter,

h. a cylindrical member axially aligned within said burner tube and surrounding said perforated conical member, said cylindrical member having a length approximately the same as the axial length of said conical member, to provide an annular passageway between said cylindrical member and said burner tube for a portion of the gas diverted from said conduit to said burner tube inlet, and

i. a baffle means for imparting tangential movement within said burner tube to gases diverted from said conduit to said burner tube inlet.

2. A burner, as recited in claim I, wherein said back pressure means comprises a perforated annulus disposed generally perpendicularly relative to the longitudinal axis of said conduit.

3. A burner,as recited in claim I, wherein said diversion means comprises a semicylindrical member, the projected area of which in a plane perpendicular to the longitudinal axis of said conduit is approximately 0.l5 to 0.25 the cross-sectional area of said conduit.

4. A burner, as recited in claim 1, wherein said conduit has a circular cross section and is of approximately the same diameter as said burner tube'and wherein the angle of intersection of said conduit and said burner tube is l 5 "25 5. A burner, as recited in elairn l, wherein said cylindrical member and said conical member are disposed such that one end thereof is disposed nearsaid baffle means and the other end thereof is disposed betweensaid nozzle and said igniter.

6. A burner, as recited in claim 1, wherein said cylindrical member and the base of said perforated conical member have a common diameter approximately -95 percent of the diameter of said burner tube. 

2. A burner, as recited in claim 1, wherein said back pressure means comprises a perforated annulus disposed generally perpendicularly relative to the longitudinal axis of said conduit.
 3. A burner, as recited in claim 1, wherein said diversion means comprises a semicylindrical member, the projected area of which in a plane perpendicular to the longitudinal axis of said conduit is approximately 0.15 to 0.25 the cross-sectional area of said conduit.
 4. A burner, as recited in claim 1, wherein said conduit has a circular cross section and is of approximately the same diameter as said burner tube and wherein the angle of intersection of said conduit and said burner tube is 15*-25 *.
 5. A burner, as recited in claim 1, wherein said cylindrical member and said conical member are disposed such that one end thereof is disposed near said baffle means and the other end thereof is disposed between said nozzle and said igniter.
 6. A burner, as recited in claim 1, wherein said cylindrical member and the base of said perforated conical member have a common diameter approximately 90-95 percent of the diameter of said burner tube. 